1. Field of the Invention
The present invention relates to systems, methods, and apparatus for creating laminate structures produced from bio-based polymer materials.
2. Background and Relevant Art
Recent architectural designs often include synthetic polymeric resin panels, which may be used as partitions, displays, barriers, lighting diffusers or decorative finishes etc. These polymeric panels are typically constructed using poly vinyl chloride (PVC), polyacrylate materials such as poly methylmethacrylate (PMMA), polyester materials such as polyethylene terephthalate (PET), poly ethylene-co-cyclohexane 1,4-dimethanol terephthalate (PETG) modified with 1,4-cyclohexanedimethanol (CHDM), glycol modified polycyclohexylenedimethylene terephthalate (PCTG), or polycarbonate (PC) materials and the like. Such synthetic polymeric resin materials are derived from byproducts of petroleum processing.
In general, such petroleum based resin panels have become popular with architects and designers as compared to decorative cast or laminated glass materials, since the polymeric resin materials may be manufactured to be more resilient, but to provide a similar transparent, translucent, and/or colored appearance as cast or laminated glass, at lower cost. Decorative resin panels may also provide greater design flexibility as compared to glass in terms of color, texture, gauge, and impact resistance. Furthermore, decorative resin panels have a fairly wide utility since they may be easily and inexpensively formed and fabricated to include a large variety of artistic colors, images, shapes, structures and assemblies.
In particular, resin panels can be economically produced in flat or three-dimensional (i.e., curved or other-shaped) forms, such as with compound curvatures. As a result, such polymer resin panel materials provide relatively wide functional and aesthetic utility, and can be used to easily change the design or function of new or existing structures. Once their useful life is over, such panels are typically disposed of within a landfill, as such large panels are not easily incorporated into existing recycle streams. Unfortunately, such panels are formed of petroleum-derived resins and are typically sent to a landfill when the product or application is no longer of use or needed. Thus, although such polymeric resin materials may be recycled, they are often simply disposed of within a landfill where they do not readily decompose or otherwise degrade and break down. As a result, there is a desire to use resin-based materials that would provide the performance benefits (e.g., impact resistance, low cost, flexibility in color, gauge, and texture) associated with petroleum derived polymeric resins but that would also be biodegradable or compostable at the end of the given material's useful life.
Along these lines, biopolymers represent a unique and responsible option for use as building materials because they are able to be composted, or are biodegradable upon disposal. Biopolymers derived from natural renewable plant or microorganism materials include polysaccharides (e.g., starch, cellulose), polyesters (e.g., polyhydroxyalconates (PHA), poly-3-hydroxybutyrate (PHB)), as well as polyesters synthesized from bio-derived monomers (e.g., polylactic acid (PLA)). Of these biopolymer materials mentioned, at least PHA, PHB, PLA, and blends thereof are compostable or biodegradable.
As used herein, the terms “biopolymer” and “bio-based polymer” refer to polymers produced or derived from living organisms or products of living organisms. For example, they may be produced from biomass. Such biopolymers are biodegradable (e.g., degradable to CO2 and water through the biological processes of microorganisms), and many are compostable (e.g., they may be inserted into an industrial composting process within which they will break down by about 90% in six months).
In contrast, conventional polymers used as building materials are typically produced from petroleum derivatives. Thus, not only do petroleum-based resins degrade very slowly (e.g., often on the order of tens or hundreds of thousands of years), but the basis for such conventional resins (i.e., petroleum), is non-replenishing and continually under pressure of exhaustion and market instability. Not surprisingly, therefore, it is increasingly important among manufacturers to consider not only the ramifications of material disposal, but also the source of the resins employed to manufacture such polymeric panels.
Of course, one will appreciate that biopolymers degrade more rapidly than petroleum-based resins and therefore can often be composted, rather than sent to a landfill. However, degradation is diametrically opposed to the notion that the best building materials resist degradation as they are required to be structurally stable. In general, biopolymer resins can be as structurally sound and long-lasting as petroleum-based resin materials, so long as the biopolymer resins are not subjected to degradation triggers. In general, these degradation triggers may include certain combinations of temperature, moisture content, biological activity and pressure over some time interval. Polymeric resin panels are often configured as a plurality of resin sheets that have been thermally fused together. Biopolymer resins are thought to be incompatible with thermal fusion processes (e.g., lamination of panels), since conventional temperatures and pressures employed are likely to initiate or accelerate degradation processes.
Another problem with subjecting biopolymer resins to thermal fusion processes is that most biopolymer resin materials are or are more likely to assume a crystalline or semi-crystalline structure, rather than an amorphous structure. Because biopolymer resins are more likely than amorphous petroleum-based resins to assume a crystalline structure, they tend to shift from transparent or semi-transparent to opaque when subjected to conventional temperatures and pressures associated with typical thermal fusion processes. This shift in transparency is believed to be a result of process-induced crystallization. For at least these additional reasons, therefore, biopolymer resins are also thought to be incompatible with the manufacture of high-end decorative and structural laminate panels, where a high degree of optical clarity, aesthetics, long term performance, and functionality are desired.
Today, the use of biopolymer materials is largely limited to packaging applications. Biopolymers are of particular use as disposable food and other product packaging materials due to their moldability and their biodegradable and/or compostable characteristics. Such packaging applications are primarily directed to single-use or short shelf-life products (e.g., food containers and the like) and the packaging material is typically discarded after a short time. Because of the short shelf-life of such products, the rapid degradability of such biopolymers has not been an issue.
Biopolymers are rarely produced in thicknesses greater than about 0.04 inch, as there is little or no demand for thicker materials. In addition to lack of commercial demand for thick gauge biopolymer sheet materials, it is well known that extrusion of easily crystallizable materials becomes increasingly difficult as the thickness of the sheet increases. Hence, there tends to be a practical processing limitation on the thickness of such biopolymer-based sheet products so as to prevent crystallization. Attempts to form thicker sheets may induce crystallization, which destroys the transparent or translucent characteristics of the material. Crystallization also dramatically decreases tensile strength and impact strength. This presents a major challenge to the use of biopolymers as building materials, because polymeric materials having a thickness of about 0.06 inch or less are of little use in architectural applications where some degree of structural integrity are required.
Finally, there are specific requirements for structural and flammability performance, as described in the International Building Code (IBC), that polymeric materials must conform to in order to be used as building materials. Currently available biopolymer polymeric sheet materials do not meet these performance criteria established in the IBC. Hence, the demand for a material that would meet the various needs of architectural applications that is also more environmentally friendly has not yet been met, for a variety of reasons.